Just as it has done for the Nexus 5 and the Nexus 10, Android 5.0 Lollipop is making its way onto last year's Nexus tablet, the 2013 version of the Nexus 7. If you've already played around with the Developer Preview, when Android 5.0 was known simply as 'L', then you've no doubt played around with Lollipop and know much of what's in store for today's update. Otherwise though, this is a pretty big deal for Nexus 7 (2013) users and Google is rolling out this update in stages.
If you're not content waiting for the OTA to hit your device, or if you're rooted and have performed all sorts of other shenanigans on your beloved Nexus, then the Factory Image is a route you might want to take. This will essentially reformat your device with Android 5.0 Lollipop coming along for the ride. It's the best way to ensure that you're getting a fresh update, but it also means that you'll be wiping your device, so a backup is in order. If that sounds fine to you then take a look at the instructions below:
1. Download the newest factory images to your PC, found here for the Nexus 7 (2013 model)
2. Unzip the file and its contents into your SDK/platform-tools folder.
3. From within your platform-tools folder, open a command prompt.
4. Type the following commands, allowing each to finish before moving onto the next:
*If using a Mac, be sure to add ./ in front of all commands (ex: ./fastboot reboot-bootloader)
adb reboot bootloader
fastboot flash bootloader bootloader-<insert-image-name-here>.img
fastboot flash radio radio-<insert-image-name-here>.img
fastboot -w update image-<insert-image-name-here>.zip
5. If you want to go back to 100% stock with a locked bootloader type:
fastboot oem lock
6. If you want to keep your bootloader unlocked, simply tap the Power button from the START screen.
7. You are now back to 100% stock.
Now, if all of that was completely over your head, then it's a better idea for you to wait for the OTA update to hit your device. Of course, if you're rooted and such, you might want to wait for a ROM to become available. When we have the OTA update file, we'll link it here for your convenience!